Method for preparing cigarette filter of cellulose acetate fibers

ABSTRACT

A method for preparing a cigarette filter of cullulose acetate fibers is provided, which is characterized by blooming a tow composed of cellulose acetate fibers, adding to the bloomed tow 1 to 20% by weight (based on the cellulose acetate fibers) of a plasticizer comprising as an ingredient at least one member selected from diacetate, dipropionate and dibutyrate esters of 1,3-butylene glycol, and gathering the thus treated bloomed tow.

United States Patent Sawada et al.

METHOD FOR PREPARING CIGARETTE FILTER OF CELLULOSE ACETATE FIBERSlnventors: Hideo Sawada; Junji Kawamoto, both of Sakai, Japan U.S. Cl.131/267; 156/180; 156/307 Int. Cl A24b 15/02 Field of Search 156/180,307; 131/267; 260/448 J; 131/10 R, 10.9

References Cited UNITED STATES PATENTS 11/1961 Touey et a1 131/2081/1962 Crawford et a1 156/161 111 3,882,878 [4 1 May 13, 1975 7/1962Touey 156/152 6/1969 Touey et al. 161/168 [57] ABSTRACT A method forpreparing a cigarette filter of cullulose acetate fibers is provided,which is characterized by blooming a tow composed of cellulose acetatefibers, adding to the bloomed tow 1 to 20% by weight (based on thecellulose acetate fibers) of a plasticizer comprising as an ingredientat least one member selected from diacetate, dipropionate and dibutyrateesters of 1,3-butylene glycol, and gathering the thus treated bloomedtow.

10 Claims, No Drawings METHOD FOR PREPARING CIGARETTE FILTER OFCELLULOSE ACETATE FIBERS This invention relates to'a method forpreparing a cigarette filter. More particularly, the invention relatesto a method for preparing a cigarette filter which comprises adding aplasticizer containing as an ingredient a diacetate, dipropionate ordibutyrate ester of 1,3- butylene glycol to cellulose acetate fibers.

A plasticizer for a cigarette filter of cellulose acetate fibersdissolves partially cellulose acetate fibers where it contacts thefibers and bonds the dissolved fibers to 'one another at random pointsof contact to retain the spaces of a filter made from the fibers and toimpart a suitable hardness to the fibers in the filter shape. Thus, theplasticizer is indispensable as a component for imparting to the filtera hardness necessary during the subsequent step of cutting the fibers ofthe filter shape into rods.

In general, triacetin, diacetate, dipropionate and dibutyrate esters ofpolyethylene glycol, dimethoxyethyl phthalate and triethyl citrate areused as plasticizers for cellulose acetate fibers constituting cigarettefilters.

In case triethyl citrate and dimethoxyethyl phthalate are used amongsuch plasticizers, it is necessary to heat filter rods at hightemperatures exceeding room temperature for 2 to 4 hours during the stepof curing the rods. Although triacetin is known as a plasticizer forcausing the curing at room temperature, it takes more than 24 hours tocomplete the curing. A diacetate, dipropionate or dibutyrate oftriethylene glycol is a plasticizer imparting a sufficient hardness atroom temperature within a relatively short time, but it is stillinsufficient with respect to the cigarette flavor.

When a plasticizer containing as an ingredient a diester compound of1,3-butylene glycol is employed according to this invention, asufficient hardness can be imparted to rods at room temperature within ashort time. The curing rate attained by the plasticizer of thisinvention is higher than the curing rate of triethylene glycol diacetatewhich is said to give a highest curing rate among conventionalplasticizers. Furthermore, the

plasticizer of this invention is odorless and non-toxic and does notdamage the flavor of cigarettes. We found the foregoing facts and havenow completed this invention based on these findings.

It is therefore a primary object of this invention to provide a methodfor preparing cigarette filters of cellulose acetate fibers in which aplasticizer having a very high curing rate is employed.

Diester compounds of 1,3-butylene glycol to be used in this inventionare compounds represented by the following general formula:

Gill 3 R-COOCH CH CH-OCOR wherein R stands for a methyl, ethyl or butylgroup, and these compounds can be used singly or in combination withother plasticizers. Since these diesters of 1,3- butylene glycol have avery high plasticizing effect, sufficient results can be obtained evenwhen they are used in smaller amounts than the amounts usually employedin the case of triacetin and triethylene glycol diacetate. Namely, inthis invention, it is preferred that the plasticizer is added in anamount of l to 20% by weight (all percent values given hereinafter areon the weight basis), especially 3 to 10%, based on the celluloseacetate fibers.

In this invention, cellulose acetate fibers are used in the form of atow obtained by gathering 5,000 to 100,000 continuous fibers having asize of l to 16 deniers. It is preferred that 10 to 30 uniform crimpsare given to the tow per 25 mm of the tow length.

Any method that can apply the plasticizer uniformly to cellulose acetatefibers may be adopted in this invention without any particularlimitation. For instance, the plasticizer is applied to both the upperand lower surfaces of the tow by a known method using a spray gun orwick. In case the amount of the plasticizer is too large, celluloseacetate fibers are so dissolved that dopes are formed. Accordingly, itis desired that the plasticizer is applied uniformly. In case the amountof the plasticizer is too small, a sufficient bonding is not obtainedamong the fibers. In view of the foregoing, in this invention it isimportant that the plasticizer is distributed uniformly in the interiorof the tow band.

In this invention, the preparation of cigarette filters fromplasticizer-incorporated tows can be conducted by methods nowindustrially conducted for the preparation of cigarette filters ofcellulose acetate fibers.

The cigarette filter obtained by the above-mentioned method of thisinvention is characterized in that inherent properties of celluloseacetate fibers are not lost and a very high curing rate can be retained.Accordingly, this invention has a great industrial value.

The method of this invention will now be illustrated by reference toExamples. In the Examples, the rod hardness was determined by thefollowing method. Namely, a load of 300 g was imposed on a horizontallyplaced sample rod through a disc having a diameter of 12 mm for 10seconds. The depth of the-indentation formed by the load was read byconsidering 0.1 millimeter to be one unit, down to one decimal place ofthe unit. A lower value indicates that the sample is hard, and a highervalue indicates that the sample is soft.

The pressure drop is expressed in terms of the resistance pressure in awater column height (mm) obtained when air was passed through a filterrod of a length of 102 mm at a rate of 17.5 ml/sec.

EXAMPLES 1 TO 7 A cellulose acetate fiber tow of a filament denier of 4and a total denier of 43,000 having 26 crimps per 25 mm of the towlength was bloomed and a diacetate of 1,3-butylene glycol diacetate or amixture of equal amounts of said diacetate and another plasticizer wasadded in a prescribed amount to the bloomed cellulose acetate fiber towby means of a plasticizer-applicator. Then, the tow is fed to a filterrod maker and wrapped by means of a rice paper. Then, it was cut into alength of 102 mm.

Such filter characteristics as the rod weight, the pressure drop and thehardness of the rod which had been allowed to stand still at 20C for lor 24 hours after preparation of the rods were determined with respectto the resulting rod. The results are shown in Table l.

The above procedures were repeated in the same manner by employingtriacetin, triethylene glycol diacetate, triethylene glycol dipropionateand tetraethylene glycol dipropionate as the plasticizer. With respectto the thus prepared rods and a rod prepared in the same manner as abovewithout use of any plasticizer, the hardness was determined after therods had been plasticizer, to stand still at 20C for 1 or 24 hours. Theresults are shown in Table 1 as Comparative Examples.

4. A method according to claim 3, in which the tow has 10 to 30 uniformcrimps per 25 mm of the tow length.

5. A method according to claim 1, wherein said plas- From the res l h wnin Table it l r ly be 5 ticizer consists essentially of said ingredient.understood that the time necessary for a rod to have a 6. A methodaccording to claim 1, wherein said plassufficient hardness (less than ishours in the case ticizer ontains at least of aid ingredi. of triacetinor triethylene glycol diacetate, but in the m Case f1,3-buty1ehe glycol(acetate 1 hour gives a 7. A method according to claim 6, wherein therefiCient hardness It is also Seen that Sufficient effect 10 mainder ofsaid plasticizer is a substance selected from can be Obtained with useof a Smaller amouht of the the group consisting of triacetin and thediacetate, diplasticizer in the case of 1,3-buty1ene glycol diacetate.propionate and dibutyrate esters f polyethylene Each of the thusobtained rods having a length of 102 mm was divided into 6 filter tipshaving a length of 17 A method aCCOfdlng t0 Clalm In which the flhtirmm. A tip of a commercially availabale Hi-Light cigal5 Cured at roomtemperature l d the amount of said rette (Trade Mark) was removed andthe thu formed ingredient applied to the fibers 1S effective to impartto tip was attached instead. As a result of the smoking the filter ahardness of less than 10 units after curing at test, it was found that aparticularly good taste and flaroom temperature for one hour, whereinhardness is vour was obtained in the case of the plasticizer commeasuredby imposing a load of 300 g onto the filter by prising 1,3-butyleneglycol diacetate. means of a disc having a diameter of 12 mm for 10 sec-Table 1 Hardness Pressure after after Example No. Plasticizer Rod WeightDrop one 24 kind by weight (g/rod) (mm H2O) hour hours Example 11,3butylene glycol diacetate 4.5 0.735 272 9.7 9.5 Example 2 do. 6.50.725 268 8.9 8.3 Example 3 do. 7.2 0.724 265 8.9 8.1 Example 4 dov 9.90.749 259 8.8 7.8 Example 5 do. 13.8 0.733 258 8.3 7.2 Example 6 equalamount mixture of 1,3-butylene 7.1 0.751 261 8.2 7.8

diacetate and triacetin Example 7 equal amount mixture of 1,3-butylcne8.3 0.748 259 8.0 7.6

acetate and triethylene glycol diacetate Comparative Example 1 not added0 0.677 247 12.1 12.7 Comparative Example 2 triacetin 8.0 0.735 259 10.58.3 Comparative Example 3 triethylene glycol diacetatc 6.3 06743 253 109.8 Comparative Example 4 triethylene glycol dipropionate 9.0 0.738 25810 8.5 Comparative Example 5 tetraethylene glycol dipropionate 9.5 0.740260 10 7.3

What we claim is: onds and measuring the depth of the indentation 1- Amethod for preparing a Cigarette filter 0f Celluthereby formed in thefilter and wherein one hardness lose acetate fibers which ompri lo minga w unit is equal to 0.1 millimeter of the depth of the indencomposed ofcellulose acetate fibers, distributing unitation, formly throughout thebloomed tow from 1 to 20% by 9. A tobacco smoke filter comprising abundle of subweight, based on the cellulose acetate fibers, of a Pstantially longitudinally extending cellulose acetate ficiler Comprisingas ah ingredient at least one "Ember bers having a size of from 1 to 16denier per fiber, said Selected from the g P Consisting of thediacetate, fibers being substantially uniformly coated with from 1prepionate and dibutyrate esters of y g y l. to 20% by weight, based onthe weight of the fibers, of and gathering th thus-tr at d l m d t t0 ra a plasticizer of at least one member selected from the filter. groupconsisting of the diacetate, dipropionate and 2. A method according toclaim 1, in which the plastidibutyrate esters f 1 3- 1 glycot cizer isadded in an amount of 3 to 10% y Weight 10. A tobacco smoke filteraccording to claim 9, in as d 0n th Cellulose acetate which the amountof plasticizer is from 3 to 10% by A method accordlhg t0 Clalm 1, Whlchthe Celhlweight, based on the weight of the cellulose acetate filoseacetate fiber tow is obtained by gathering 5,000 to bers 100,000continuous fibers having a size of 1 to 16 deni- 6O ers.

1. A METHOD FOR PREPARING A CIGARETTE FILTER OF CELLULOSE ACETATE FIBRESWHICH COMPRISES BLOOMING A TOW COMPOSED OF CELLULOSE ACETATE FIBERS,DISTURBING UNIFORMLY THROUGHOUT THE BLOOMED TOW FROM 1 TO 20% BY WEIGHT,BASED ON THE CELLULOSE ACETATE FIBERS, OF A PLASTICIZER COMPRISING AS ANINGREDIENT AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF THEDIACETATE, DIPROPIONATE AND DIBUTYRATE ESTERS OF 1,3-BUTYLENE GLYCOL,AND GATHERING THE THUS-TREATED BLOOMED TOW TO FORM A FILTER.
 2. A methodaccording to claim 1, in which the plasticizer is added in an amount of3 to 10% by weight based on the cellulose acetate fibers.
 3. A methodaccording to claim 1, in which the cellulose acetate fiber tow isobtained by gathering 5,000 to 100,000 continuous fibers having a sizeof 1 to 16 deniers.
 4. A method according to claim 3, in which the towhas 10 to 30 uniform crimps per 25 mm of the tow length.
 5. A methodaccording to claim 1, wherein said plasticizer consists essentially ofsaid ingredient.
 6. A method according to claim 1, wherein saidplasticizer contains at least 50% by weight of said ingredient.
 7. Amethod according to claim 6, wherein the remainder of said plasticizeris a substance selected from the group consisting of triacetin and thediacetate, dipropionate and dibutyrate esters of polyethylene glycol. 8.A method according to claim 1, in which the filter is cured at roomtemperature and the amount of said ingredient applied to the fibers iseffective to impart to the filter a hardness of less than 10 units aftercuring at room temperaturE for one hour, wherein hardness is measured byimposing a load of 300 g onto the filter by means of a disc having adiameter of 12 mm for 10 seconds and measuring the depth of theindentation thereby formed in the filter and wherein one hardness unitis equal to 0.1 millimeter of the depth of the indentation.
 9. A tobaccosmoke filter comprising a bundle of substantially longitudinallyextending cellulose acetate fibers having a size of from 1 to 16 denierper fiber, said fibers being substantially uniformly coated with from 1to 20% by weight, based on the weight of the fibers, of a plasticizer ofat least one member selected from the group consisting of the diacetate,dipropionate and dibutyrate esters of 1,3-butylene glycol.
 10. A tobaccosmoke filter according to claim 9, in which the amount of plasticizer isfrom 3 to 10% by weight, based on the weight of the cellulose acetatefibers.